Method and apparatus for transferring substrates

ABSTRACT

An apparatus for continuously transferring substrates such as tablets from a rotary, double-sided tablet press to a second location is provided. The apparatus comprises a flexible conveying means on which transfer units adapted to receive the substrates are mounted. The flexible conveying means travels along a path that is coincident with those portions of the tablet press where tablets are ejected.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/967,414, filed on Sep. 28, 2001, now U.S. Pat. No.6,742,646, entitled “Systems, Methods and Apparatuses for ManufacturingDosage Forms” (MCP0295), and incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to methods and apparatuses fortransferring substrates, such as tablets, from one location to another.

BACKGROUND OF THE INVENTION

Double-sided tablet presses are commonly used in the pharmaceuticalindustry for making tablets. Their configuration is well known.Typically, they comprise a rotor having dies located along itsperiphery. The rotor rotates through first and second compression zones.In each compression zone, powder is fed to dies, optionally the powderis precompressed and then compressed within the dies, and finallyfinished tablets are ejected from the press. Because double-sided tabletpresses contain two compression zones, with each revolution of the rotortwo sets of tablets are made. The tablets are ejected from oppositesides of the press at first and second tablet ejection zones. Theejected tablets are conventionally transferred away in bulk by anejection chute leading to a collection container such as a drum orhopper.

Commonly assigned, copending U.S. patent application Ser. No.09/967,414, the disclosure of which is incorporated herein by reference,discloses a transfer device capable of handling substrates such astablets having a high degree of friability and softness. It is arotating device comprising a plurality of transfer units attached to aflexible conveying means, such as a belt. It is preferably used fortransferring substrates within a continuous process from one operatingunit to another, for example from a compression apparatus to a coatingapparatus. The flexible conveying means follows a path from the firstoperating unit to the second operating unit. The velocity and positionsof the transfer units are synchronized with the operating units to whichit is coupled, so that substrates can be smoothly captured from thefirst operating unit and released to the second operating unit. Thetransfer units comprise retainers for holding the substrates. Theretainers are preferably flexible and constructed from an elastomericmaterial. In a preferred embodiment, the retainers are circular andcomprise segmented fingers of elastomeric material.

Applicants have now designed a transfer device having transfer unitscomprising inner and outer, side by side retainers that sequentiallyrather than simultaneously capture substrates. The device may be used totransfer tablets or other substrates, preferably from a rotary,double-sided tablet press to a second location. The transfer units aremounted on a flexible conveying means that travels along a pathcoincident with those portions of the tablet press where tablets areejected. In one embodiment, the transfer units are adapted to receivefirst tablets at a first substrate receiving station of the apparatuslocated proximal to the first tablet ejection zone of the tablet press,and adapted to receive second tablets at a second substrate receivingstation located proximal to the second tablet ejection zone of thetablet press.

SUMMARY OF THE INVENTION

The invention provides an apparatus for transferring substrates,comprising: a) a flexible conveying means; b) a plurality of transferunits mounted to said conveying means, each transfer unit adapted tohold first and second substrates; c) a cam track defining a path from afirst substrate receiving station, passing through a second substratereceiving station, and then to a substrate transfer station; and d)means for driving said conveying means along said cam track.

The invention also provides an apparatus for transferring tablets from adouble-sided tablet press comprising first and second tablet ejectionzones to a second location, said apparatus comprising a plurality oftransfer units mounted to a flexible conveying means, each transfer unitadapted to hold first and second tablets, a cam track defining a pathfrom a first substrate receiving station located proximal to the firsttablet ejection zone, passing through a second substrate receivingstation located proximal to the second tablet ejection zone, and then toa substrate transfer station located at the second location; and meansfor driving said conveying means along said cam track.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a conventional double-sided tablet press.

FIG. 2 depicts a transfer apparatus according to the invention coupledwith the tablet press of FIG. 1.

FIG. 3 is a cross-sectional view of a transfer apparatus according tothe invention.

FIGS. 4-8 illustrate a preferred embodiment of a transfer unit.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts a conventional, double-sided tablet press 1. The tabletpress 1 comprises a rotor 2 having a plurality of dies 3 around itsperiphery. FIG. 1 depicts 12 dies. Accordingly, each revolution of thistablet press produces 24 tablets.

Tablet press 1 comprises first and second powder feeders 4 a, 4 b, firstand second precompression rollers 5 a, 5 b (which are optional), andfirst and second main compression rollers 6 a, 6 b. First powder feeder4 a is located on the opposite side of rotor 2 from second powder feeder4 b. First precompression roller 5 a is located on the opposite side ofrotor 2 from second precompression roller 5 b. Likewise, first maincompression roller 6 a is located on the opposite side of rotor 2 fromsecond main compression roller 6 b. A first compression zone 11 acomprises first powder feeder 4 a, first precompression roller 5 a andfirst main compression roller 6 a. A second compression zone 11 bcomprises second powder feeder 4 b, second precompression roller 5 b andsecond main compression roller 5 b. Tablets 10 a; 10 b are ejected fromopposite sides of tablet press 1 at a first tablet ejection zone 7 a anda second tablet ejection zone 7 b.

The tablet press operates as follows. Powder is fed from the firstpowder feeder 4 a to dies 3 passing thereunder as rotor 2 rotates in thedirection shown by arrows a. This powder is optionally precompressed bythe first precompression roller 5 a, and compressed by the first maincompression roller 6 a into tablets 10 a. Tablets 10 a are ejected fromthe dies 3 at first tablet ejection zone 7 a. Empty dies 3 next passunderneath the second powder feeder 4 b and new powder is fed to thedies 3. The new powder is optionally precompressed by the secondprecompression roller 5 b, and compressed by second main compressionroller 6 b into tablets 10 b. Tablets 10 b are ejected from the dies 3at the second tablet ejection zone 7 b.

The apparatus for transferring substrates (also referred to herein asthe transfer apparatus) may be coupled with a double-sided tablet pressas described above, as shown for example in FIG. 2. In particular, thetransfer apparatus may be used to retrieve tablets from a double-sidedtablet press and transfer them to a second location for furtherprocessing, for example coating. Advantagously, the transfer apparatustransfers the tablets on a continuous basis.

Referring to FIG. 2, the transfer apparatus 12 comprises a flexibleconveying means 13, shown here as a belt, to which a plurality oftransfer units 14 are attached. The flexible conveying means may be madeof any suitable material, one example of which is a composite consistingof a polyurethane toothed belt with reinforcing cords of polyester orpoly-paraphenylene terephthalamide (Kevlar®, E.I. duPont de Nemours andCompany, Wilmington, Del.). Other flexible materials, such as chains,linked belts, metal belts, and the like can be used as the flexibleconveying means.

The transfer apparatus can be driven by any suitable power source suchas an electric motor. In one embodiment, the transfer apparatus islinked to the tablet press and driven by mechanical means through agearbox (not shown) that is connected to a main drive motor (not shown).In this configuration the velocity and positions of the individualtransfer units of the transfer apparatus can be synchronized with thedies of the tablet press.

In one embodiment of the invention, as shown in FIG. 3, the transferapparatus includes a drive pulley 20 and an idler pulley 21. A driveshaft 22 connects drive pulley 20 to a main drive train (not shown).Drive shaft 22 drives drive pulley 20 to rotate. Drive pulley 20 hasteeth that engage teeth 23 disposed on the interior of flexibleconveying means 13, which in turn moves the transfer apparatus in thedirection of arrows b shown in FIG. 2. Idler pulley 21 has teeth thatengage flexible conveying means 13 as well, which causes the idler torotate with flexible conveying means 13.

The transfer apparatus further comprises a cam track 24 that preciselydetermines the path for the flexible conveying means 13. The path of camtrack 24, the pitch distance between the transfer units 14, the pitch ofthe flexible conveying means 13, and the gear ratio between the drivingmeans of the transfer apparatus and the driving means of the tabletpress (as well as the driving means of other operating units to whichthe transfer apparatus is coupled) are all selected such that thetransfer apparatus is precisely aligned with the tablet press and anyother operating units linked to it. As each operating unit rotates, thetransfer apparatus remains synchronized and phased with each, such thata precise and controlled transfer from one operating unit to another isachieved.

The velocity and positions of the transfer units 14 are matched to thevelocity and positions of the dies 3 in the tablet press along twoportions of the path defined by the cam track 24. As shown in FIG. 2,the path travels through a first substrate receiving station 18 a, asecond substrate receiving station 18 b, and a substrate transferlocation 19. Substrate transfer location 19 may be located for exampleat a second location remote from the tablet press, for instance proximalto another operating unit 17.

First portion 16 a of the path defined by the cam track is an arccoincident with tablet press rotor 2 when it passes through the firsttablet ejection zone 7 a of the tablet press. Second portion 16 b of thepath is an arc coincident with the tablet press rotor 2 when it passesthrough the second tablet ejection zone 7 b. Substrates are receivedalong these two arc lengths.

A preferred transfer unit 14 is depicted in FIG. 4. Each transfer unitis adapted to hold first and second substrates in a side-by-sidefashion. Each transfer unit 14 generally includes a pair of plungershafts 25, one or preferably more than one cam follower 26, a pluralityof bearings 27 to retain the plunger shafts 25, a spring 28, a plate 29that secures the plunger shafts 25 to cam follower 26 therebycontrolling their movement, first retainer 30 a and second retainer 30b. Preferably, each transfer unit 14 is attached to flexible conveyingmeans 13 in a cantilever configuration so that retainers 30 a, 30 b arecantilevered over the path of the substrates.

Retainers 30 a, 30 b are preferably flexible and constructed from anelastomeric material. Retainers 30 a, 30 b flex upward as shown in FIGS.6-8 to grasp substrates, shown as tablets 100, therein. Substrates areejected from the retainers 30 a, 30 b by pushing down on them, therebyflexing the retainers. Once released, the retainers 30 a, 30 b flex backto their original positions to receive further substrates. In apreferred embodiment, the retainers 30 a, 30 b are circular and includesegmented fingers of elastomeric material as shown in FIG. 5, but neednot be so constructed. The retainers 30 a, 30 b need only be flexibleenough to flex, hold a substrate, and release the substrate.

First and second retainers 30 a and 30 b are disposed side-by-sidewithin each transfer unit. In one embodiment of the invention, eachtransfer unit is attached to the center of the flexible conveying meansas shown in FIG. 2, such that the first and second retainers 30 a and 30b are disposed on either side of the flexible conveying means. Viewedfrom the perspective of forward movement of the flexible conveying meansalong the path, the first retainer 30 a is located on the outside ofeach transfer unit, while second retainer 30 b is located on the insideof each transfer unit, i.e., closer to the center of the transferapparatus. This inner/outer configuration, coupled with the pathfollowed by the cam track, allows the transfer unit to pick up onesubstrate at a time, as described below.

Referring to FIG. 4, riding in cam track 24, cam follower 26 is mountedso that it can move up and down as shown in FIGS. 4-8. Plate 29 iscoupled to cam follower 26. Spring 28 biases the plate 29 and camfollower 6 to an upper position. Plate 29 is also coupled to eachplunger shaft 25, so that movement of the plate 29 will cause movementof the plunger shafts 25. Each plunger shaft 25 is mounted within atransfer unit 14 by a plurality of bearings 27 that permit verticalmovement of the plunger shafts 25. The plunger shafts 25 are mounted sothat one end of each plunger shaft 25 can move into the respective spacein which a substrate is retained to eject it from the associatedretainer, as shown in FIG. 8. The plunger shafts 25 and bearings 27 maybe made of any suitable material.

The transfer apparatus operates as follows. As shown in FIG. 2, flexibleconveying means 13 is moved along the path defined by the cam track 24and wheels 15 a, 15 b, 15 c in the direction of arrows b. This directseach transfer unit 14 in series to the first substrate receiving station16 a. Here, a transfer unit 14 comes into proximity with a die 3containing a first tablet in the first tablet ejection zone 7 a of thetablet press. The first retainer 30 a of the transfer unit 14 alignswith the die 3. The first tablet is ejected from the die 3 by thepunches of the tablet press and into the retainer 30 a as shown in FIGS.6-8. Retainer 30 b remains empty.

Further rotation of the transfer apparatus by the drive pulley causesthe flexible conveying means 13 and its attached transfer units 14 totravel farther along the path shown by arrows b. Retainer 30 a continuesto hold a first tablet therein. When the transfer unit 14 reaches thesecond substrate receiving station 16 b it comes into proximity with adie 3 containing a second tablet in the second tablet ejection zone 7 bof the tablet press. The second tablet is ejected from the die 3 andinto retainer 30 b. Now, retainers 30 a and 30 b contain first andsecond tablets, side-by-side in the transfer unit.

As each full transfer unit 14 reaches substrate transfer location 19,cam track 24 pushes on the cam follower 26, which pushes on plate 29.Plate 29 moves the plunger shafts 25, which in turn move down andcontact the retained substrates. The substrates are pushed past theelastomeric collets and ejected from the retainers. Plunger shafts 25return to their original upward position.

The transfer device may alternatively comprise rotatable transfer units,as described in commonly assigned, copending U.S. patent applicationSer. No. 09/967,414, particularly as shown in FIGS. 77-81 therein. Thisis useful for example with elongated dosage forms, i.e., caplets thatare compressed horizontally but then must be coated in a verticalposition. As shown in FIG. 80 of the '027 application, each transferunit 602 comprises of a dosage form holder 608 rotatably mounted in ahousing. Each dosage form holder comprises two sets of flexibleretainers 630, 630B, one for entry of a substrate 630 and one for exitof a substrate 630B. During transit along path defined by the cam track606, the dosage form holder rotates 90 degrees due to motion of a camfollower 626 within the cam track 606. An ejector pin assembly 612enters through holes 608A in the dosage form holder 608 to eject thesubstrate. The dosage form holder 608 rotates 90 degrees again,returning to its horizontal position to begin the cycle over again.

The following non-limiting example further illustrates the claimedinvention.

EXAMPLE

Acetaminophen-containing tablets are compressed in a double-sided tabletpress, Fette model 3090. The press operates at 2000 tablets per minuteper side, or 4000 tablets per minute total. The tablet press is coupledto a coating apparatus via a transfer device according to the invention.The transfer device, tablet press and coating apparatus are all drivenby a common motor, and are synchronized. The transfer device comprisestransfer units, each with first and second retainers, and receivesacetaminophen tablets from both sides of the tablet press. The firstretainer receives first tablets from one side of the tablet press, andthe second retainer receives second tablets from the other side of thetablet press. The transfer units proceed to a coating apparatus, wherethey are ejected and coated with gelatin.

1. An apparatus for transferring substrates, comprising: a) a flexibleconveying means; b) a plurality of transfer units mounted to saidconveying means, each transfer unit adapted to hold first and secondsubstrates; c) a cam track defining a path from a first substratereceiving station, passing through a second substrate receiving station,and then to a substrate transfer station; and d) means for driving saidconveying means along said cam track, wherein the path positions theflexible conveying means on opposite sides of the first and secondsubstrate receiving stations.
 2. The apparatus of claim 1, wherein thetransfer units are mounted to said conveying means in a cantileverconfiguration.
 3. The apparatus of claim 1, wherein each transfer unitcomprises first and second retainers made of an elastomeric material andcomprising segmented fingers, said first retainer adapted to hold afirst substrate and said second retainer adapted to hold a secondsubstrate.
 4. The apparatus of claim 3, wherein said first and secondretainers are located side by side within each transfer unit.
 5. Theapparatus of claim 4, wherein the transfer units are mounted to thecenter of the conveying means, such that said first and second retainersare positioned on either side of the conveying means.
 6. The apparatusof claim 1, wherein the path positions the conveying means on the insideof the first substrate receiving station, and on the outside of thesecond substrate receiving station.
 7. The apparatus of claim 1, whereinthe path positions the flexible conveying means on the outside of thefirst substrate receiving station, and on the inside of the secondsubstrate receiving station.
 8. The apparatus of claim 1 furthercomprising vacuum means for applying a vacuum to said substrates whilethey are held by the transfer units.
 9. The apparatus of claim 1,wherein said transfer units are rotatably mounted to said conveyingmeans, such that said transfer units are capable of being rotated whilethey travel along said cam track.
 10. The apparatus of claim 9, whereinsaid apparatus further comprises a rotatable actuator arm linked to saidtransfer units such that as said actuator arm rotates, said transferunits rotate.
 11. An apparatus for transferring tablets from adouble-sided tablet press comprising first and second tablet ejectionzones to a second location, said apparatus comprising a plurality oftransfer units mounted to a flexible conveying means, each transfer unitadapted to hold first and second tablets, a cam track defining a pathfrom a first substrate receiving station located proximal to the firsttablet ejection zone, passing through a second substrate receivingstation located proximal to the second tablet ejection zone, and then toa substrate transfer station located at the second location; and meansfor driving said conveying means along said cam track, wherein the pathpositions the conveying means on opposite sides of the first and secondsubstrate receiving stations.
 12. The apparatus of claim 11, whereinsaid double-sided tablet press comprises a rotor that travels throughthe first and second tablet ejection zones, and said path comprisesfirst and second portions, said first portion being an arc coincidentwith said rotor when it travels through the first tablet ejection zoneand a second portion being an arc coincident with said rotor when ittravels through the second tablet ejection zone.
 13. The apparatus ofclaim 11, wherein each transfer unit comprises first and secondretainers made of an elastomeric material and comprising segmentedfingers, said first retainer adapted to hold a first tablet and saidsecond retainer adapted to hold a second tablet.
 14. The apparatus ofclaim 13, wherein said first and second retainers are located side byside within each transfer unit.
 15. The apparatus of claim 13, whereinthe transfer units are mounted to the center of the conveying means,such that said first and second retainers are positioned on either sideof the conveying means.
 16. The apparatus of claim 13, wherein the pathpositions the conveying means on opposite sides of the first and secondsubstrate receiving stations.
 17. The apparatus of claim 16, wherein thepath positions the conveying means on the inside of the first substratereceiving station, and on the outside of the second substrate receivingstation.
 18. The apparatus of claim 16, wherein the path positions theflexible conveying means on the outside of the first substrate receivingstation, and on the inside of the second substrate receiving station.19. The apparatus of claim 14, wherein said first retainer is adapted toreceive tablets at said first substrate receiving station and saidsecond retainer is adapted to receive tablets at said second substratereceiving station.
 20. The apparatus of claim 14, wherein said pathpositions said first retainer to receive tablets at said first substratereceiving station and positions said second retainer to receive tabletsat said second substrate receiving station.
 21. The apparatus of claim11 further comprising vacuum means for applying a vacuum to saidsubstrates while they are held by the transfer units.
 22. The apparatusof claim 11, wherein said transfer units are rotatably mounted to saidconveying means, such that said transfer units are capable of beingrotated while they travel along said cam track.
 23. The apparatus ofclaim 22, wherein said apparatus further comprises a rotatable actuatorarm linked to said transfer units such that as said actuator armrotates, said transfer units rotate.
 24. A method for transferringsubstrates using the apparatus of claim 1, which comprises in sequence:a) receiving a first substrate at said first substrate receivingstation; b) receiving a second substrate at said second substratereceiving station; and c) transferring said first and second substratessimultaneously to said substrate transfer station.
 25. The method ofclaim 24, wherein steps a) through c) are repeated as a continuousprocess.